rjh@ihuxj.UUCP (Randolph J. Herber) (12/21/83)
According to the___ Astronomical____________ Almanac_______ for___ the___ year____ 1982____ by the Nautical Almanac Office, U.S. Naval Observatory, Washington, D.C. and Her Majesty's Nautical Almanac Office, Royal Greenwich Observatory, London, on page M10 of the glossary: parsec______: the distance at which one astronomical____________ unit____ subtends an angle of one second of arc; equivalently the distance to an object having an annual parallax________ of one second of arc. on page M2 of the glossary: astronomical____________ unit____ (a.u.): a unit of length, originally defined as the length of the semimajor_________ axis____ of the Earth's orbit_____. It is now defined dynamically by using Kepler's third law: n_^2 * a_^3 = k_^2 * (1+m_) where a_ is the semimajor axis of an elliptic orbit (in a.u.), n_ is the sidereal mean____ motion______ (in radians per ephemeris_________ day___), m_ is the mass (in solar masses), and the value of the Gaussian gravitational constant k_ is defined to be exactly 0.01720209895. As determined from this definition the semimajor axis of the Earth's orbit is 1.000000031 a.u. The underscored words and symbols were italized in the original text. The reason for the repeat is that I misspelled 'parsec' as 'parasec' in the first version. Randolph J. Herber, Amdahl Systems Engineer, ..!ihnp4!ihuxj!rjh -- Randolph J. Herber, Amdahl Systems Engineer, ..!ihnp4!ihuxj!rjh, c/o IH 1C220, AT&T Bell Labs, Naperville, IL 60566, (312) 979-6554 or AT&T Cornet 8-367-6554, or Amdahl Corp., Suite 250, 6400 Shafer, Rosemont, IL 60018, (312) 692-7520